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Hs-TnI in Suspected ACS: High-STEACS Trial
Study Questions:
Does incorporating high-sensitivity troponin I (hs-TnI) measurements in the evaluation of patients presenting to the emergency department with suspected acute coronary syndrome (ACS) improve outcomes?
Methods:
The High-STEACS trial adopted a stepped-wedge, cluster-randomization of 10 hospitals in Scotland, and consisted of 2 phases: a validation phase of 6 months during which the contemporary cardiac troponin assay was used to guide clinical decisions, and an implementation phase of 6-24 months during which only results of the high-sensitivity assays were disclosed. Both assays were measured throughout the trial, and hs-TnI gender-specific cutoffs were used to reclassify patients with troponins below the diagnostic threshold as having myocardial injury. Registries were reviewed for the primary outcome of subsequent myocardial infarction (type 1 or 4b) or cardiovascular death within 1 year of the initial presentation. Outcomes were compared between patients who had been reclassified by the hs-TnI assay before, and those after the implementation phase.
Results:
A total of 48,282 consecutive patients with suspected ACS were included, of which 39% presented during the validation phase and 61% during the implementation phase. A total of 10,360 (21%) had hs-TnI concentrations above the reference cutoffs, and of those, 1,771 (17%) were reclassified by the high-sensitivity assay. There was no difference in the primary outcome between patients enrolled in the validation phase (n = 1,106, 6%) and implementation phase (n = 1,480, 5%). Similarly, there were no differences in primary, secondary, or safety endpoints between the validation and implementation phase in patients reclassified by the hs-TnI assay, who were also more likely due to undergo coronary angiography (11% vs. 4%) and have longer hospitalization (51 vs. 21 hours). Conversely, patients without myocardial injury and the study population overall had a shorter hospitalization. Of note, only one-third of patients reclassified had a diagnosis of type 1 myocardial infarction.
Conclusions:
Systematic implementation of a hs-Tn assay in the evaluation of patients suspected with ACS was not associated with either improved or worse outcomes.
Perspective:
In this modern era of heightened awareness, rapid initiation of medical therapies, door-to-balloon times <60 minutes, and drastically better cardiovascular outcomes, it would be a surprise to see a diagnostic test improve outcomes. Nonetheless, High-STEACS is a well-designed trial that provides a wealth of information. Most importantly, its findings highlight on one end the potential for decreasing hospitalization with rapid rule out, and on the other hand the challenge in discerning type 1 myocardial infarction – for which evidence-based therapies are available – and other types of injury, which often lead to unnecessary testing, costs, and their associated risks. With refinement of thresholds, and incorporation of a sound clinical assessment, the balance may still sway towards the adoption of hs-TnI in improving the cost-effectiveness of care.
Keywords: ESC Congress, ESC18, Acute Coronary Syndrome, Coronary Angiography, Biomarkers, Cost-Benefit Analysis, Diagnostic Imaging, Diagnostic Tests, Routine, Emergency Service, Hospital, Myocardial Infarction, Myocardial Reperfusion Injury, Outcome Assessment, Health Care, Risk, Troponin I
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